The present invention relates to a filtration device and method finding particular utility in reducing the amount of silt, sedimentation and debris in water entering storm drains.
In response to tighter guidelines imposed by the federal Environmental Protection Agency under the Clean Water Act, additional regulatory attention is being focused on controlling silt and sediment found in storm, construction site and other sources of water runoff. Federal and state agencies have issued mandates and developed guidelines regarding the prevention of non-point source pollution. These mandates affect water runoff from storms, construction sites, and other sources. Such laws and regulations have a significant impact on not only how runoff water may be channeled and diverted, but also on, for example, the ways that contractors can dispose of excess or unwanted water from constructions sites. With respect to construction sites, the Environmental Protection Agency (EPA) has a goal of having developers prevent eighty percent of general contaminants, such as unwanted, site-generated sediment, from entering inlet drains.
One of the drawbacks to existing filtering devices is that silt, sedimentation, mud and other debris can build up quickly, causing filtering devices to clog. As clogging begins, water flow decreases, which leads to a back-up of excess, unfiltered water. Back-ups may create additional regulatory, environmental, aesthetic and structural problems. Many systems have circumvented back-up of excess water by providing by-pass overflow features; however, while an overflow feature solves the immediate problem, the overflow water remains unfiltered, thereby defeating the primary intent of the filtration device.
When a filtering device's capacity is reduced to the point that it no longer adequately functions, the filter must be removed and either be disposed of or cleaned. Filtration devices can be difficult and time consuming to remove. For example, when a filtration device is attached to the underside of an inlet grate, sediment is collected underneath the grate. To change or clean a filter, the inlet grate must first be removed. Next, either the device must be removed (to be cleaned or disposed of) or the sediment must be removed from the device. Removal of the device can be difficult, as it may have a large mass of sediment that is very heavy. In this case, removal is at least taxing and time-consuming, possibly cumbersome and may require lifting machinery. If the device does not hold a large volume of sediment, then removal will be more easily accomplished, but also must be done more frequently. In addition to the constraints and problems associated with cleaning or changing a filtering device, timing also creates a problem. Oftentimes, clogging of filtering devices occurs during periods of heavy water flow, such as seasonal or other flooding periods. This presents an immediate need for cleaning or replacing a filter coupled with circumstances that make the task even more difficult, onerous, and time-consuming.
Accordingly, there exists a need for better devices, systems and methods for filtering sediment from water entering storm drains, specifically those which provide ease of installation; can be easily cleaned or changed, even during periodic flooding; prevent unwanted back-up of excess water; filter nearly all or all of the water that comes through the inlet; and are cost effective.